Lubricating oil



Patented Sept. 30, 1941 LUBRICATING OIL Hans G. Vesterdal, Elizabeth, N.J., assignor to Standard Oil Development Company, a corporation ofDelaware No Drawing. Application December 29, 1937, Serial No. 182,253

8 Claims.

The present invention relates to improved lubricating oils and method ofpreparing the same. It particularly relates to highly refined stablelubricating oils which are suitable for use under the extreme oxidizingconditions prevailing in internal combustion engines as, for example, inmotor, Diesel and aeroplane engines. This improved highly refinedlubricating oil, which is highly resistant to oxidation and sludging, isprepared by treating refined lubricating oil with a small quantity of aboron halide.

It is well known that highly refined lubricating oils are very desirablefor use in internal combustion engines. These oils, however, as a resultof the extended refining processing steps are prone to oxidize morereadily than less highly refined oils. One explanation of this is thatthe'refining steps tend to remove natural inhibitors present in the oilwhich are not removed in aless highly refined 'oil. The oxidationtendency of oil is aggravated when subjected to the high temperaturesand extreme oxidizing conditionsprevailing in internal combustionengines. The oxidation of the oil results both in the formation ofacidic substances which cause excessive corrosion and in the formationof oxidation products which are insoluble in the oil and consequentlysettle out in the form of a sludge. This resulting sludge formationgreatly decreases the lubricating quality of the oil and may result inbearing seizure and engine failure. This tendency of a highly refinedlubricating oil to oxidize may be overcome to a large extent by. theprocess of adding oxidation inhibiting substances. These oxidationinhibitors, while preventing undue oxidation of the oil, however do havethe disadvantage in that most of them tend to increase the Sligh valueof the oil. These substances have. the further disadvantage in that theymust be handled separately and must be blended in the oil in the correctproportion.

The process of the present invention prepares an oxidation and sludgingresisting highly refined lubricating oil by treating a highly refined orpartly refined oil with a boron halide, preferably boron fluoride. Thelubricating oils to be treated according to the present invention may beany lube distillate. The preferred stocks are lubricating oils which aremainly paraffinic in nature or oils which have been cresyl phosphate,aniline, acetone, and also low boiling liquid hydrocarbons as, forexample, liquid propane and butane. Suitable materials to be treatedaccording to the present invention are, for example, oils prepared byacid treating and dewaxing of so-called parafiin distillate which issecured from paraflin type crude, such as Pennsylvania crude, or byselective solvent treating of lube oil distillates from any kind of acrude oil, provided, however, that most of the unsaturated and aromaticcompounds are removed by such pretreatment so that the oil to b treatedwith boron halide has a. bromine number of below 1, preferably below 0.5and a gravity in the range from 24 to 35 A. P. I. and viscosities in therange from 75 seconds Saybolt at 100 F. to 200 seconds Saybolt at 210 F.

These refined lubricating oils'are treated with less than of boronfluoride, preferably with about .2% of boron fluoride. The conditions oftreatment are preferably at room temperature and atmospheric pressure,although temperatures up to 300-400" F. may be employed. The preferredmethod is to mix the oil with boron fluoride at the desired temperaturefor one to 30 minutes. Longer time of contact may be used although 30minutes generally is sufiicient. At the end of this period, the mixtureis stripped with superheated steam or an inert gas at about atemperature of from 300 to 550 F. or vacuum stripped until all thecorrosive compounds derived from the boron fluoride have been removed.

The following examples are given for the purpose of illustrating theinvention and are not to be. construedas limiting the invention in anymanner whatsoever.

Example 1 A paraflindistillate derivated from a paraffin l l a fiashofapproximately 305 F. and a viscosity pretreated with a cheaperrefiningagent such as sulphuric acid, aluminum chloride, or with selectivesolvents which have the ability to segregate hydrocarbons having ahigher ratio of hydrogen to carbon from the hydrocarbons having a lowerratio of. hydrogen to carbon as, for example, dichlor ethyl ether andalso liquid sulphur: dioxide, phenol, ortho anisidine, ethylenediacetate, triphenyl phosphate, acetonitrile, 1 furfur'al, resorcinoldiacetate, tri- Saybolt of 72 at F., was treated in order to remove thewax constituents. The dewaxed oil was then led to a distillation unitinwhich the feed stock was flashed under high vacuum producing lubricatingstocks having viscosities at 210 -F. of about 43 and 52 seconds Sayboltrespectively. This latter fraction having a gravity of approximately 25A. P. I. and a flash of approximately 450 F. was then treated withapproximately an equal quantity of phenol. The resulting lubricating oilhad a gravity of approximately 30, a flash of 450 F. and a viscosity at100 of about 312.

A portion of this refined oil was treated with about 0.5% of boronfluoride at room temperature with suitable agitation. This saturatedmaterial was then treated with preheated steam at atemperature of from330 to 350 F. to remove the boron fluoride. This treated oil was thentested for sludging tendency as measured by the Sligh value* as well asa sample of the oil which was not treated with boron fluoride.-

The results were as follows:

Sludge determination igh value I y Mg. sludge/ g. of oil Boron fluoridetreated oil 2.5 Untreated. oil V 7.8

*Sligh test: A method for determining the sludglng tendency in alubricating oil described' m an A.' T. M. Report Committee D2, page 22,1927. The Shgh test on the'above samples was modified in that it was runover a period of 24 hours instead of the 2 ,4; hours described in thereport.

at room temperature with suitable agitation.

This mixture was then h eated to a temperature of about 300 F. and wassteam stripped. at a temperature of about 300 to 350? for a period orabout minutes. The sludging tendency of the boron fluoride treated oilwas determined as well as the sludging tendency of the untreated oil.The results were as follows:

Sludge determination Sligh value Boron fluoride treated oi1 2 4Untreated oil 21.5

E rahtple 3 V 'The lubricating 011-a 'r::smiii151e 2 was mixed with 0.06gm. of boron fiu rideperiOO cc. ofoil at room temperature for 15minutes. The mixture was then steam stripped at 330 to 350 F.

for 15 minutes. The sludg'in ten denicy ofithe treated and untreatedoils was dete'rniineda's be-.

fore: a

" Sludge determination Sligh value Boron fluoride treated oil 3.8Untreated oil .21.5

Example 4 V o c'c. 01" the lubric ating loil of gamma 2 were mixed with0.3 gram of boron fluoride at 250-260" F. for about 5 to 10 minutes. Themixture'was heated up' further and steam stripped at 330-350 F. for 15minutes. The sludging tend! any of the treated and untreated oils wasdetermined as before, as well as the viscositie s at '100" F. and 210 F,(and viscosity indices):

The lubricating oil or Example 2 was mixed with 0.5% boron fluoride atroom temperature for approximately .l ,rninutes. I, The mixture was &ences.

then steam stripped "at teni'peratui'e'sfro'r'n "330 to 350 F. Thesludging tendency of the untreated oils was determined as describedabove.

Sludge determination Sligh value 1 Boron fluoride treated oil 2.4

Untreated oil 21.

Example 6 The boronfiuoride treated oil as described in Examples 3, 4and 5, and the untreated oil, were tested in order to determine theiroxidation rate. The results of these tests were as follows:

Oxidation Bromine rate) No.

Untreated oil 181 0.03 Oil treated withi 0.5% boron fluoride 172 0.15%boron fluoride i 0.06% boron fluoride .i

*A test to determine the tendency oi the oil to oxidize. Oilis bubbledin a closed circulatory system through 10 cc. 01 the respective oilswhich are held at a temperature of 200 C. At 15 minute intervals theamount of oxygen remaining unconsumed is measured,

and the volume of oxygen absorbed by the oil calculated by difier ings.V

Example 7 200 grams of a well refined, motor oil (S. A. E.- 30) whichhad excellent qualities except for its high Sligh value, were mixed withless thanp0.1 gm. of boron fluoride. at room temperature for itminutes.The mixture was heated up to 350 F. and steam, strippedfor 15 minutesatthis temperature. vThe sludging tendency of the treated and untreatedoils was determined as before: n i y H Sludge determination f Slighvalue Boron fluoride treated oil Untreated oil V Ezcdmple 8 Alubricating motor oil S. A. E. 30 was tested to determine the oxidationrate and the sludging tendency as measured by' the Sligh number aswellras by the Cone test. To this oil. was then added 2% of naturalinhibitors which tend to decrease the oxidation rate. The oxidation rateand Sligh value were determined on this blend; The blend was thentreated with 0.3% of boron fluoride in the manner described above andthe same tests were then made. The results wer'e' as follows: i

-Oxida- Sludging Zion en e y 91 rate Sligh No. es

Lubricating oil 8. A. E. so 1. 2 '0. 88 Lubricating oil S. A. E. 30 2%natural inhibitor as 48.6 Blend treated with 0.3% boron fluov ride V 643.9 0.30

r *A method for determining the tendency of an oil to deposit-sludgematter upon a heated metalllc' surface. It. consists in slowly droppinethe 011 to be tested over a heated metal cone which is generally steel.The cone has a circumferential groove-milled out in a screw fashion onthe periphery thereby allowing a time of contact of about one minutebetween the heated steel surface and the oil. Atot'al volume of 60 cc.of oil is released from a dropping funnel'ov'r a period of two hours. V

desired value but for lubricating oils it is preferred to fuse'about'250 0. since 1t represents approximately the extremetemperatureto which oils are ordlnarily exposed in the internalcombustion engine.

After the entire volume of oil is run over the metallic surface the coneldWaShed with naptha to completely remove the adhering oil without dsturbing the deposit left on the cone. The cone is then weighed and thencrease in weight of the cone due'to the depositleft thereon by the 011is expressed in grams. 1 e

r V I Emapze 9; e r

A 'lii ris atih soi as a mament 11 was mixed with approximately 10% of amixture The above oxidation rate is an average 01 the first three read-The temperature of the cone may be any of di and tri isobutylene. Theunblended oil was treated with 0.5% boron fluoride and the blend wastreated with approximately of boron fluoride. The sludging tendencies ofboth the untreated and treated oilswere then determined with. thefollowing results:

% di and tri isobutylene 100% lubri- 90% lubricateating oil eating oilSligh No. on untreated oil 7.8 Sligh No. on treated oil 9.8 2. 5

It is particularly applicable to the preparation of high grade motoroils, of electrical transformer oils and the like. If necessary, theoils may be dewaxed before or after the boron fluoride treatment and/orthey may be treated either before or after the boron fluoride treatmentwith other reagents such as sulphuric acid, aluminum chloride, clay orother treating agents, or with selected solvents such phenol, chlorex,nitrobenzene and the like, or with light hydrocarbon solvents. Asphalticand oxygen-containing materials are preferably removed before the boronfluoride treatment.

The invention is not to be limited by any theory or method of operationbut only by the following claims in which it is desired to claim allnovelty in so far as the prior art permits.

I claim:

1. Process of preparing improved oxidation and sludging resistantlubricating oils comprising treating a previously refinedlubricating oilsubstantially free of unsaturated materials with a small amount of aboron halide in an amount less than 0.5%.

2. Process in accordance with claim 1 in which said boron halide isboron fluoride.

3. Process of preparing improved oxidation and sludging resistantlubricating oils comprising treating a refined lubricating oilsubstantially free of unsaturated materials and characterized by havinga bromine number less than 1 with a small quantity of boron fluoride inan amount less than 0.5%.

4. Process in accordance with claim 3 in which said bromine number isless than 0.5.

5. Process of preparing improved oxidation and sludging resistantlubricating oils comprising treating a refined lubricating oilsubstantially free of unsaturated materials and characterized by havinga bromine number less than .5 with from 0.01% to 0.5% of boron fluoridefor a sufiicient length of time to increase the stability of the saidoil, followed by stripping of the treated product to remove the boronfluoride and corrosive compounds.

6. The process of preparing an oxidation and sludge resisting highlyrefined lubricating oil comprising treating a paraflinic base oiloflubrieating oil consistency to remove wax constituents, flashing thedewaxed oil under high vacuum, treating the distillate fraction withap-.

proximately an equal quantity of phenol, removing the raflinate fractionand dephenolizing it, treating the resultant raflinate oil with a smallquantity of a boron halide in an amount less than 0.5% for a sufficientperiod of time to increase the stability of the said oil and strippingthe treated product to remove boron fluoride and corrosive compounds.

7. Process according to claim 6 in which the amount of boron fluorideemployed is between 0.01% and 0.5%.

l 8. Process for preparing an oxidation and sludge resisting highlyrefined lubricating oil comprising subjecting a lubricating oil fractionof a crude petroleum to a refining treatment to produce a refined oilhaving a bromine number below 1, a gravity between 24 and A. P. I., anda viscosity between seconds Saybolt at F. and 200 seconds Saybolt at 210F., then treating said refined oil with a small amount of oil to removeboron fluoride and corrosive compounds.

HANS G. VESTERDAL.

